Device for stunning an animal for slaughter

ABSTRACT

The invention relates to a device for stunning an animal for slaughter, for instance a pig, which device includes: transporting means for transporting an animal for slaughter through the device; at least two head electrodes for placing against the head of the animal; at least one body electrode for placing against the head of the animal; a first electrical component connected to the head electrodes for carrying through the brain of the animal a first current pulse; and second electrical component connected to the body electrode for carrying through the body of the animal a second current pulse.

BACKGROUND OF THE INVENTION

The invention relates to a device for stunning an animal for slaughter,for instance a pig, which device comprises: transporting means fortransporting an animal for slaughter through the device; at least twohead electrodes for placing against the head of the animal; at least onebody electrode for placing against the body of the animal; firstelectrical means connected to the head electrodes for carrying throughthe brain of the animal a first current pulse; and second electricalmeans connected to the body electrode for carrying through the body ofthe animal a second current pulse.

Such a device is described in applicant's Netherlands patent applicationNL-A-92 00487.

In respect of this Netherlands patent application it is an object of theinvention to effect a stunning of the animal for slaughter in veryreliable and rapid manner and to calm the animal for slaughter.

A further object of the invention is to spare the animal needlesssuffering and to cause loss of consciousness to occur as quickly aspossible.

Another object of the invention is to embody the stunning device suchthat it has a large processing capacity so that the device can beapplied on an industrial scale.

During delivering of the current pulses damage to and bleeding inmuscles can occur as a consequence of the thereby occurring strongmuscle contractions. The meat can hereby deteriorate in quality. In thisrespect it is an object of the invention to embody the stunning devicesuch that the danger of convulsive muscle contractions is considerablyreduced, whereby the meat can be of better quality.

SUMMARY OF THE INVENTION

In order to realize the above stated objectives the invention provides adevice in accord with the first paragraph, in which said first currentpulse comprises an alternating current component with a first basicfrequency f₁ of at least 100 Hz; said second current pulse comprises analternating current component with a second basic frequency f₂ which islower than f₁ and which begins a maximum of 8 s after the start of thefirst current pulse; and during the contact between the electrodes andthe animal for slaughter the relative velocity between the electrodesand the animal for slaughter is substantially zero. It should be notedthat the time period between the beginning of the second current pulseand the start of the first current pulse may be negative.

With the first, relatively high-frequency current pulse a stunning takesplace and docility occurs in the short term. Delivery of the secondcurrent pulse causes a disfunction of the heart rhythm, which alsoprovides docility in the longer term.

It is noted that the use of a basic frequency f₁ of at least 100 Hz hasthe effect of causing less convulsions.

The transporting and the stated time span provide a large processingcapacity. It is important here to obtain a good contact between theelectrodes and the animal for slaughter in order to minimize thepercentage of incompletely stunned animals.

In respect of the stated basic frequency it is noted that any finitesignal can be thought of as being built up of a number of frequencies.By the term "basic frequency" is understood the lowest repetitionfrequency which is recognizable in the waveform and which can be derivedfor instance from the repetition frequency of crests, valleys, zero-axiscrossings or the like.

The alternating current components in the current pulses can inprinciple take any desired form, for example that of a sine, a block, arepeating pulse, a sawtooth etc. These alternating current componentscan optionally be superimposed on another component for the whole timeduration of a current pulse or during a part thereof. This othercomponent can itself also consist of an alternating current component ora direct current component.

Claims 2, 3 and 4 give a number of possible values of f₁ in order ofincreasing preference. It has been found that the electric current whichis required for inducing loss of conscience increases generally over 1kHz.

Preferably f₂ <1 kHz.

By preference f₂ <100 Hz.

The use of the electrical source frequency as stated in claim 7 has theadvantage of very easy availability.

The choice of frequency for the second current pulse as stated in claim8, f₂ =(15±10) Hz, easily induces a heart fibrillation resulting in apermanent heart disfunction and thereby docility of the animal forslaughter.

In Meat Science 31 (1992), 481-491, experiments are described whichrelate to carrying through the head of an animal for slaughter a currentpulse consisting of an alternating current with a frequency of about1600 Hz. In contrast to these experiments the invention provides adevice which is capable of effecting in the correct manner a rapiddisturbance of the heart, whereby a considerable lengthening of theperiod of docility of the animal for slaughter is achieved. A deviceaccording to the invention provides, in contrast to the saidexperiments, the option of use on industrial scale.

Furthermore reference is made to "Advances in Animal Wellfare Science"by M. W. Fox and L. D. Mickley, 1986, "Cardiac arrest stunning oflifestock and poultry", pages 1-30, provides a general survey ofparameters and combinations thereof known in the art of stunning animalsfor slaughter. This general survey does not suggest the use of twocurrent pulses having different frequencies. Furthermore in this surveythere is no suggestion of provisions in order to ensure that therelative velocity between the related electrodes and the animal forslaughter is substantially zero.

It is generally the objective to cause the time durations of the currentpulses on the one hand to be sufficiently long to cause the stunning totake place as rapidly and effectively as possible, while on the otherhand a short time duration of the current pulses is aimed for, wherebythe treatment speed can be as high as possible. In this latter respectthe diverse electrodes can be reciprocally movable along thetransporting means such that during delivery of the current pulses theelectrodes move at substantially the same speed as the animal forstunning, which in the combination according to the inventioncontributes to a surprisingly good stunning in a short time span.

Preferably, in the device according to the invention, the time durationt₁ of the first current pulse is a certain amount larger than the timeperiod between the start of the first current pulse and the beginning ofthe second current pulse.

Surprisingly, by the use of an overlap between the two current pulses itis possible to stun an animal for slaughter with substantially lessconvulsions, reflexes, muscle contractions and the like, resulting in abetter meat quality and a more easy handling of a stunned animal forfurther treatment. It has been found that minimum convulsions and musclecontractions occur at a frequency of the first current pulse amountingto about 800 Hz. This is the subject matter of claims 3 and 4. Moregenerally, the strength of the convulsions decreases with frequencies ofthe first current pulse of over 100 Hz.

Preferably, the said amount specified above and in claim 9 is at least0,2 s.

Preferably, the device is characterized in that the time durationbetween the beginning of the first current pulse and the end of thesecond current pulse amounts to 1,5-8 s.

It has appeared that the animal's sensation of pain after stunning iseffectively suppressed if t₁ ≧1 s.

In another embodiment the device may be characterized in that the timeduration t₂ of the second current pulse satisfies the relation 1 s<t₂<3,5 s.

Furthermore the invention relates to a device of the type set forthabove, said device comprising two body electrodes for placing againstthe body of the animal such that the second current pulse is carried fora substantial part through the heart region of the animal via these twobody electrodes. It appears that the second current pulse flowingthrough the heart region is effective for a very quick and effectivestunning.

Also the invention relates to a device of the type set forth above,comprising transporting means for transporting an animal for slaughterthrough the device such as a conveyor belt or restrainer, wherein duringthis transport the animal assumes a known position, for instance suchthat its median plane extends at least more or less horizontally orvertically.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be elucidated with reference to the annexeddrawing, wherein:

FIG. 1 shows a perspective view of a pig lying on a restrainer, whereina device according to the invention is shown highly schematically inoperating situation; and

FIG. 2 shows a partly broken away perspective view of another embodimentof the device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2, lying on a conveyor belt 1, a so-calledrestrainer, is a pig 2 which is to be stunned. According to theinvention use is made for this purpose of a number of electrodes, in theembodiment drawn two head electrodes 3, 4 and two body electrodes 5, 35which are connected to an electrical supply device 6 for successivelycarrying a current pulse through the head of the pig 2 via the headelectrodes 3, 4 and carrying a second current pulse through the heartregion of the animal via the body electrodes 5, 35. In FIG. 1 thereference numeral 7 designates a transformer which provides a powersupply source 8 with the correct voltage and current. The headelectrodes 3, 4 receive current via a first switch 9, while passage ofcurrent via body electrodes 5, 35 is controlled by a second switch 10.These switches are controlled by a control unit 11 which ensures that afirst current pulse is carried through head electrodes 3, 4 followed bya second current pulse via body electrodes 5, 35.

The diverse relevant parameters of the first and the second currentpulses are defined in claims 2-14.

For the sake of clarity the power supply device 6 is not drawn in FIG.2.

The conveyor 1 comprises a chain 12 which is driven by non-drawn meansand bears blocks 14 each provided with a central longitudinal recess 13.The longitudinal recess 13 has a form such that the breast bone of pig 2can be accommodated therein. This conveyor has a construction such thatthe pig remains lying docilely thereon in a fixed position.

Via a frame 15 with rails 16, 17 a carriage 19 is displaceable by meansof wheels 18 in lengthwise direction with conveyor 1. This carriage 19can be driven by a cylinder 20 which is energized by non-drawn means forreciprocating displacement of carriage 19. Because the carriage 19 isdriven in the transporting direction 21 at the same speed as conveyor 1the electrodes 3, 4, 5, after having been placed in the desiredposition, can move along with the pig 2 for a period of time.

The electrodes 3, 4 are carried by a pivot arm 22 which is pivotable bymeans of cylinders 23, the driving whereof is likewise not drawn.Herewith the electrodes 3, 4 can be arranged with some force against thehead of pig 2.

Electrode 5 is carried by a plate 24 which is movable toward and awayfrom pig 2 by means of a cylinder 25. This latter engages onto an arm 26which, together with an arm 27 parallel thereto, supports the plate 24.

By making use of the above described construction the electrodes 3, 4, 5can be pressed with a sufficiently great pressure against the pig 2,whereby the transfer resistance between the electrodes and the pigremains limited an a relatively high current can be realized at arelatively low voltage.

It is noted that in the embodiment of FIG. 2 the second body electrode35 as according to FIG. 1 is omitted. The second current pulse iscarried in this case through the body electrode 5 and at least one ofthe head electrodes 3, 4.

Attention is further drawn to the fact that the positioning of the bodyelectrodes 5, 35 in FIG. 1 is only shown by way of example. In anotherembodiment the second body electrode 35 can for instance engage on thefront side of the breast of the animal.

I claim:
 1. A device for stunning an animal for slaughter, which devicecomprises:transporting means for transporting the animal for slaughterthrough the device; at least two head electrodes configured to be placedagainst the head of the animal; at least one body electrode configuredto be placed against the body of the animal; first electrical means fordelivering through the brain of the animal a first current pulse with analternating current component having a first basic frequency f₁ of atleast 100 Hz, said first electrical means connected to said headelectrodes; and second electrical means for delivering through the bodyof the animal a second current pulse with a second basic frequency f₂which is lower than f₁ and which begins a maximum of 8 seconds after astart of the first current pulse, said second electrical means connectedto said at least one body electrode, wherein during contact between theelectrodes and the animal for slaughter, a relative velocity between theelectrodes and the animal for slaughter is substantially zero.
 2. Thedevice as claimed in claim 1, wherein said first electrical means isconfigured such that f₁ ≧200 Hz.
 3. The device as claimed in claim 2,wherein said first electrical means is configured such that f₁=(800±600) Hz.
 4. The device as claimed in claim 3, wherein said firstelectrical means is configured such that f₁ =(800±300) Hz.
 5. The deviceas claimed in claim 1, wherein said second electrical means isconfigured such that f₂ <1 kHz.
 6. The device as claimed in claim 5,wherein said second electrical means is configured such that f₂ <100 Hz.7. The device as claimed in claim 6, wherein the device is connected toan electrical source and said second electrical means is configured suchthat f₂ equals the frequency of the electrical source.
 8. The device asclaimed in claim 6, wherein said second electrical means is configuredsuch that f₂ =(15±10) Hz.
 9. The device as claimed in claim 1, whereinsaid first electrical means is configured such that a time duration t₁of the first current pulse is larger than a time period between thestart of the first current pulse and the beginning of the second currentpulse.
 10. The device as claimed in claim 9, wherein said firstelectrical means is configured such that the time duration t₁ of thefirst current pulse is ≧0.2 seconds larger than the time period betweenthe start of the first current pulse and the beginning of the secondcurrent pulse.
 11. The device as claimed in claim 1, wherein said firstelectrical means is configured such that a time duration between thestart of the first current pulse and an end of the second current pulseis about 1.5-8 seconds.
 12. The device as claimed in claim 1, whereinsaid first electrical means is configured such that a time duration ofthe first current pulse is ≧1 second.
 13. The device as claimed in claim1, wherein said first electrical means is configured such that a timeduration of the first current pulse is <3 seconds.
 14. The device asclaimed in claim 1, wherein said second electrical means is configuredsuch that a time duration t₂ of the second current pulse satisfies therelation 1 second<t₂ <3.5 seconds.
 15. The device as claimed in claim 1,comprising two body electrodes configured to be placed against the bodyof the animal such that the second current pulse is carried for asubstantial part through a heart region of the animal via the two bodyelectrodes.
 16. The device as claimed in claim 1, wherein thetransporting means comprises at least one of a conveyor belt and arestrainer, and wherein during transport the animal assumes a positionsuch that a median plane of the animal extends at least one ofhorizontally and vertically.